Apparatus for simultaneous formation of overcasting and securing stitches in superposed fabric plies

ABSTRACT

A SEWING MACHINE FOR OVERCASTING THE EDGES OF TWO SUPERPOSED FABRIC PLIES EACH WITH A SEPARATE OVERCASTING THREAD AND FOR FORMING A SINGLE LINE OF SECURING STITCHES WHICH SIMULTANEOUSLY UNITES SAID SUPERPOSED FABRIC PLIES AND ANCHORS SAID SEPARATE OVERCASTING THREADS.

United States Patent [72] Inventor Roger J. Ross Roselle, NJ.

[21] Appl. No. 880,781

[22] Filed Nov. 28, 1969 [45] Patented June 28, 1971 [73] Assignee The Singer Company New York, N.Y.

[54] APPARATUS FOR SIMULTANEOUS FORMATION 0F OVERCASTING AND SECURING STITCHES IN SUPERPOSED FABRIC PLIES 3 Claims, 5 Drawing Figs.

[52] U.S.Cl.... 112/162 [51] 1nt.Cl D05b1/20 [50] FieldofSearch 112/162, 163,269

[56] References Cited UNITED STATES PATENTS 1 .978,9l7 10/1934 Story at a] 112/162 3,342,150 9/1967 Tretow et al.... 112/162 3,246,620 4/1966 Sigoda et al. l 12/ 163X Primary Examiner-James R. Boler At!0rneys-Marshall J. Breen, Chester A. Williams, Jr. and

Robert E. Smith ABSTRACT: A sewing machine for overcasting the edges of two superposed fabric plies each with a separate overcasting thread and for forming a single line of securing stitches which simultaneously unites said superposed fabric plies and anchors said separate overcasting threads.

PATEN'IF U JUH28 am 3, 5 7,492

sum 1 or 2 I N VIiN '1 0R. Roger J. Ross BY WITNESS= W 9 (Luv m ATTORNEY PATENTED JUH28 I971 SHEET 2 OF 2 INVENTOR. Roger J. Ross Km, TORNEY APPARATUS FOR SIMULTANEOUS FORMATION OF OVERCASTING AND SECURING STITCI'IES IN SUPERPOSED FABRIC PLIES BACKGROUND OF THE INVENTION Previously known techniques for overcasting the edges of superposed plies of fabric and uniting the plies by a securing seam have involved either a plurality of passes through one or more sewing machines, first to overcast the ply edges and then to unite the plies, or such known techniques have required a complicated special sewing machine in which two stitching points are provided in tandem so that the two successive separate sewing operations of overcasting and uniting can take place in tandem during one pass of the fabric through the special machine. Both' of these known techniques present economic drawbacks, the former obviously requiring multiple handling of the fabric by the machine operator, and the latter requiring a costly sewing machine, which moreover because of the tandem stitching arrangement, is not adapted for sewing comers or any but the most gradually curved edges.

It is an object of the present invention toprovide a sewing mechanism in which a single reciprocating needle simultaneously forms a seam which secures the fabric plies together and anchors a plurality of overcasting threads which are positioned about the edges of the fabric plies being sewn. The mechanism of the present invention thereby retains the simplicity of conventional single needle sewing apparatus, and does not adversely influence work manipulation about sharp turns or abrupt corners.

The object of this invention is attained by the combination of a stitch forming mechanism capable of forming a single line of securing stitches with a plurality of thread laying fingers equal in number to the number of fabric plies being secured together, and means for shifting the thread laying fingers to opposite sides of the fabric plies during alternate needle reciprocations so as to present to the sewing machine needle threads which cover the edges of each of the fabric plies.

DESCRIPTION OF THE DRAWINGS With the above and additional objects and advantages in view as will hereinafter appear, this invention comprises the devices, combinations, and arrangements of parts hereinafter described and illustrated in the accompanying drawings of a preferred embodiment in which:

FIG. 1 represents an end elevational view of a sewing machine to which this invention has been applied and in which portions of the sewing machine frame are broken away more clearly to illustrate the mechanism,

FIG. 2 represents a side elevational view of the sewing machine of FIG. 1 with portions of the machine frame broken away to expose the mechanism,

FIG. 3 is an enlarged diagrammatic representation of the mechanism for shifting the thread laying fingers of this invention and includes a representation of the work guide and the sewing needle,

FIG. 4 is an enlarged elevational view of the work fabric guide means, and

FIG. 5 is a perspective view of the work fabrics as stitched using the mechanism of this invention.

Referring to FIGS. 1 and 2 of the drawings, this invention is illustrated as applied to a sewing machine of the type which is described in detail in the Knaus U.S. Pat. No. 2,238,796, Apr. 15, 1941 to which reference may be had. The sewing machine includes a frame indicated generally at 11 in which is journaled a main drive shaft 12 which is provided with connections as described in the above referred patent for imparting endwise reciprocatory movement to a thread carrying needle 13 and also imparts operative movement to a needle thread takeup member 14 and to a fabric feeding dog I5.

Illustrated at 16 is a presser bar which may be supported and biased toward the feed dog as in the referenced U.S. Pat. No. 2,238,796; however, this invention requires that work fabrics which are presented to the sewing needle 13 must be guided in a novel fashion and preferably this is accomplished by a unique presser device 17. The presser foot is formed with an upwardly inclined toe portion 18 carrying at its right hand edge, as viewed in FIG. 2, a wall portion 19 which supports a fabric ply-separating block 20 beneath the presser foot toe portion 18. The presser foot illustrated in FIGS. 1 and 2 is adapted to guide two superposed plies of fabric to the action of the needle 13, the top fabric ply being directed in the space between the presser foot toe portion I8 and the ply separating block 20, while the lower ply of fabric is directed beneath the ply separating block 20. As illustrated in FIG. 2, the wall portion 19' preferably extends forwardly and beneath the ply separating block 20 and serves as an edge guide for both of the fabric plies which are being directed to the stitching point.

As indicated in FIG. 3 in which the presser foot portions are indicated diagrammatically, and in FIG. 4 apertures 21 and 22 are provided in the presser foot toe portion and in the ply separating block, respectively, for passage therethrough of the needle. As shown in FIGS. 1 and 4 the ply separating block 20 adjacent the path of needle reciprocation is preferably formed with a notch 23 which, as will be described hereinbelow, serves the purpose of accommodating the thread laying fingers of this invention. The presser device, as is conventional, is biased downwardly in opposition to a work supporting throat plate 24 through which the feed dog I5 operates also in opposition to the presser device.

For producing the uniting and edge covering seam of this invention, the mechanism illustrated in FIGS. I and 2 differs from that described in the above referred U.S. Pat. No. 2,238,796 in that the stitch forming instrumentalities cooperating with the needle 13 to produce a securing stitch preferably differ from those shown in the referenced patent. Any conventional four-motion chainstitch looptaker of the type which cooperates with the needle to produce a securing stitch of the type referred to as Federal Type 401 could be used with this invention. As shown in the drawings, a looptaker 25 is arranged in the sewing machine beneath the feed dog 15 and is of the type having a thread eye adapted to carry a locking thread into concatenation with thread carried by the needle. The looptaker may be carried for oscillation by a shaft 26 to which a rock arm 27 is clamped. The rock arm may be oscillated to impart loop seizing and shedding motion to the looptaker by means of a pitrnan 28 connected to the rock arm and driven by the main drive shaft 12. Any suitable mechanism (not shown) may be used for imparting lateral needle avoiding movement to the looptaker 28. Also illustrated in FIG. 1 is a looper thread controlling cam 28 on the main drive shaft 12 and thread guiding means 29 associated therewith to provide a takeup mechanism for the looper thread. a

As thus far described, the sewing machine is capable of uniting two super posed plies of fabric with a conventional twothread chainstitch. The needle thread for the formation of such a chainstitch may be directed from a suitable source of supply to a thread tensioning device 30, the needle thread takeup l4, and thence to the'thread carrying needle 13. The looper thread for formation of the twothread chainstitch may be directed from a suitable source of supply (not shown) to a thread tensioning device 31, then to the looper thread takeup guide 29 and to the thread carrying loop taker 25 For applying each of the covering threads, which are overcast about the edge of each of the plies of fabric which are united by the securing stitch, a pair of thread laying fingers 40, 41 are provided, each being secured to a carrying block 42 for movement in unison relatively to the plies of fabric being stitched. The mechanism for supporting and actuating the thread laying fingers is best illustrated in FIGS. 2 and 3 in the drawings. For imparting movement to the thread laying fingers transversely of the line of stitch formation of the securing seam a bellcrank lever 43 is pivotally supported on the fulcrum pin 44 carried in the machine frame. An upstanding arm 45 of the bellcrank lever 43 is pivotally connected to the carrying block 42 by the pivot pin 46 which protrudes into a guide slot formed in s support bracket 48 carried on the sewing machine frame. The horizontal arm 49 of the bellcrank 43 carries a follower stud which tracks a cam groove 51 formed in the rear face of a cam disc 52 rotatably supported on a cam shaft 53 on the front of the sewing machine frame. For imparting shifting movement to the thread laying fingers alternately on opposite sides of the plies of fabric being sewn, a lever 54 is fulcrumed on a pin 55 in the sewing machine frame and pivotally connected by means of a pivot pin 56 to a connecting link 57 which is pivoted in turn by the pivot pin 58 to the carrying block 52. The lever 54 carries between its extremities a follower stud 59 which tracks a cam groove 60 formed in the front face of the cam disc 52.

The cam grooves 51 and 60 for influencing shifting movement of the thread laying fingers 40 and 41 are preferably cut so as to produce one complete cycle of shifting movement of the thread laying fingers during each complete revolution of the cam disc 52. Preferably, the cam disc 52 is driven at onehalf the rate of the main drive shaft 12 so that one complete cycle of movement of the thread laying fingers occurs during two successive reciprocations of the needle. To this end the cam disc 52 is preferably driven by a counter shaft 61 journaled in bearings 62, 63, and 64 in the machine frame by means of a pair of meshing bevel gears 65, 66. The shaft 61 is driven from the main drive shaft 12 at one-half the speed thereof by means of a timing belt 67 and sprocket wheels 68 and 69 on the shafls 12 and 61 respectively.

In FIG. 3 the guide means for presenting work fabrics to the action of the stitch forming instrumentalities is indicated quasi-diagrammatically in order to indicate the manner in which the thread laying fingers 40 and 41 move alternately on opposite sides of the respective fabric plies 70 and 80. It will be understood that the uppermost thread laying finger will move 'altemately above and below the top fabric ply 70 while the lower thread laying finger 41 will move alternately above and below the bottom fabric ply 80, and that during each needle penetration the thread laying fingers 40 and 41 will be shifted to the left as viewed in FIG. 3 to present loops of the threads carried thereby for penetration of the needle. FIG. illustrates the appearance of the resulting seam formation. lt will be apparent that the superposed plies of fabric 70 and 80 will be united by a row of stitches indicated by the needle thread limbs 90, the edge of the upper ply 70 will be overcast by thread 100 carried by the thread laying finger 40 while the edge of the lower ply 80 will be overcast by thread 110 carried by the lower thread laying finger 41. The edge covering threads 100 and 110 may be directed from sources of supply (not shown) each to one of the thread tension devices 111, 112, then to thread guiding eyelets 113 which may be carried on the support bracket 48, and then to the thread laying fingers 40 and 41, respectively. It is only necessary that the number of thread laying fingers correspond to the number of plies of fabric which are to be united and that each of the thread laying fingers be shiftably supported and driven so as to alternately move above and below its respective ply of fabric and present a thread loop for penetration by the needle on alternate sides of the ply on alternate needle penetrations.

The sewing machine of this invention is advantageous in that it provides for the overcasting of the edges of the plies and for the formation of a uniting seam simultaneously with the operation of a single fabric penetrating needle. By this arrangement curved surfaces may be sewn and sharp comers may be executed. In contrast with conventional overedging machines, moreover, the mechanism of this invention provides for higher sewing speeds because the movements of the thread laying fingers take place at one-half the frequency of movements of overedge loopers in conventional overedging machines. The resultant reduction in inertia forces and vibration is a distinct advantage of this invention.

I claim:

1. A sewing machine for overcasting the edges of a plurality of superposed fabric plies each with a separate overcasting thread, and for forming a sin e line of securing stitches which simultaneously unites said p urality of superposed fabric plies and anchors said separate overcasting threads, comprising a thread carrying needle, drive means for reciprocating said needle endwise to penetrate said fabric plies, guide means for directing said fabric plies in spaced relation into the path of said needle, stitch forming instrumentalities cooperating with said needle to form a line of securing stitches uniting said fabric plies, a plurality of thread laying fingers equal in number to said superposed fabric plies to be overedged, and means for shifting said thread laying fingers in unison transversely of said line of securing stitches and each about the edge of a respective one of said fabric plies into cooperative thread laying relation with said needle on opposite sides of said respective fabric plies during alternate needle penetrations.

2. A sewing machine for overcasting the edges of a plurality of superposed fabric plies as set forth in claim 1 in which said means for shifting said thread laying fingers comprises a single rotary actuator drivingly connected with a first linkage for shifting said thread laying fingers transversely of the line of securing stitches and with a second linkage for shifting said thread laying fingers to opposite sides of said respective fabric plies, and means operatively interconnecting said single rotary actuator with said needle reciprocating drive means to impart recurring motion to said thread laying fingers at one-half the frequency of needle reciprocation.

3. A sewing machine for overcasting the edges of a plurality of superposed fabric plies as set forth in claim 1 in which said guide means comprises a presser foot formed with a needle accommodating aperture and formed with separate fabric guiding channels which converge and join rearwardly of the needle accommodating apertures, said separate fabric guiding channels of said presser foot being formed with sufficient clearance therebetween to accommodate said thread laying fingers. 

